Using real world data to analyse self-consumption and self-sufficiency of residential PV systems with and without storage

Increasing the self-consumption and self-sufficiency of PV systems has benefits for both the end users, in term of increasing the revenue of their investment and for the local distribution grid, in term of reducing the demand and interaction of distributed renewable systems with the grid. This study sets out to utilise real world performance data in order to analyse the self-consumption (SC) and self-sufficiency (SS) of residential PV systems with and without associated battery storage. The data shows that both the SC and SS have a strong relationship with the system generation/consumption ratio. For the systems without battery storage, the obtained data shows that SC decreases sharply with increasing generation/consumption ratio to reach ~28% on average for systems where annual generation equals consumption. Furthermore, the data suggests that for PV systems without storage, it is unlikely to achieve a SS higher than 40% even at a PV generation that is many times the consumption. For the systems with storage, the data suggests that the existence of a battery with a nominal capacity of 5.22 kWh (which is the capacity of some of the analysed systems) can lead to an increase of ~25% in SC. Also, for the systems with battery storage, the SS can reach more than 75% at generation/consumption ratios >1. Increasing the battery capacity to 8.19 kWh does not significantly improve SC and SS. Detailed analysis showed that battery settings, PV panel orientation and the presence of loads such as electric heating have a critical effect on SC and SS.